Centerless grinder assembly and method of operating the same

ABSTRACT

A centerless grinder assembly for machining elongate workpieces and method of operating same are disclosed. The centerless grinder comprises a work wheel for removing stock from an associated workpiece, a regulating wheel arranged to cooperate with the work wheel in removing the stock from the workpiece and a support device arranged between the work wheel and a regulating wheel for supporting the workpiece during machining operations.

This is a division of application Ser. No. 08/635,328 filed Apr. 19,1996 U.S. Pat. No. 5,674,106, which is a CIP application Ser. No.08/598,549 filed Feb. 8, 1996 Abandoned.

FIELD OF THE INVENTION

The present invention pertains to centerless grinders. Moreparticularly, the present invention pertains to a centerless grinderhaving sensors which detect at least the position of an elongateworkpiece and send signals which are processed to control the taperedconfiguration of the workpiece machined by the centerless grinder.

BACKGROUND OF THE INVENTION

A centerless grinder is a manufacturing machine tool which can be usedto grind elongate cylindrical workpieces such as wires, rods, pins, golfclub shafts and the like. The workpiece may require a constantcross-sectional diameter. Alternatively, the workpiece may requirevarious tapered sections including slight tapered sections and abruptdiametrical changes.

The process of using a centerless grinder to machine such workpieces isalso known as grinding the workpieces or removing stock from theworkpiece to obtain the desired configuration. Centerless grinders areparticularly useful where precision tolerances are required and whereparticularly accurate profiles are desirable.

Centerless grinders include three main components. A work wheel, whichis also known in the art as a grinding wheel, a regulating wheel and awork rest blade. The work wheel is the machine component that usuallyperforms the actual removal of stock from the workpiece. The work wheelthus determines the surface finish and the overall configuration of theworkpiece. The surface texture of the work wheel can be varied dependingupon the particular grinding operation desired.

The regulating wheel is the machine component which directs and guidesthe workpiece to the work wheel. The regulating wheel is alsoresponsible for driving the workpiece and causing rotation thereofduring the grinding process.

The work rest blade is the machine component which provides support forthe workpiece during machining (i.e., grinding) operations. Theregulating wheel will cause the workpiece to rotate on the work restblade while the work wheel removes the amount of stock required toobtain the desired diameter or taper of the associated workpiece. Priorart work rest blades include horizontal or angled support surfaces. Theparticular orientation of the work rest blade surface may be selected inaccordance with the required configuration of the completed workpiece.

Royal Master Grinders, Inc. of Oakland, N.J. developed a centerlessgrinder having photoelectric sensors which detect the position of thetrailing end of the workpiece during machining operations. The detectedsignal is processed and causes the regulating wheel to change itsposition with respect to the work wheel so that the configuration of theworkpiece is modified. As the trailing end of the workpiece is detectedby additional sensors, further signals are generated and processed whichmay cause the regulating wheel to again change its position with respectto the work wheel. Accordingly, the machined workpiece may include oneor more tapered sections. The tapered sections may be gradual, orabrupt, depending upon the desired configuration of the workpiece. RoyalMaster's aforementioned prior art centerless grinder is widely used incommercial practice.

A modified embodiment of the aforementioned centerless grinder includesindependently adjustable individual sensors which can be arranged at adesired position with respect to the workpiece. Such independentlyadjustable individual sensors may require various adjustments in orderto set the parameters of the associated centerless grinder machine toperform grinding operations which are sufficient to produce a workpiecehaving a customized configuration.

U.S. Pat. No. 5,480,342 discloses a control system which controls theposition of a movable regulating wheel of a centerless grinder. Thecontrol system includes a sensor which measures the feed rate at whichthe workpiece is fed between the regulating wheel and the work wheel.The rate of movement of the regulating wheel is adjusted based on thecontinuously calculated position and feed rate of the workpiece duringthe machining process. This prior art centerless grinder is deficientbecause it is not versatile for use with workpieces of various lengths.In particular, the aforementioned centerless grinder may not be able toproperly grind workpieces which are of a length that the trailing end ofthe workpiece is positioned behind all of the sensors during thegrinding process. Thus, the sensors are not be able to detect movementof the workpiece at the required locations.

SUMMARY AND OBJECTS OF THE INVENTION

The present invention overcomes the shortcomings of prior art centerlessgrinders by providing a novel centerless grinder which has theversatility to machine workpieces having various lengths. The centerlessgrinder of the present invention can machine a wide variety of elongatedworkpieces, such as wires (e.g., wires used for heart catheterization),rods, pins, golf club shafts, etc.

The centerless grinder of the present invention comprises a work wheelfor removing stock from a workpiece, and a regulating wheel arranged tocooperate with the work wheel in removing the stock from the workpiece.Support means are arranged between the work wheel and the regulatingwheel for supporting the workpiece during machining operations. Thecenterless grinder also includes a slidable sensor bank which has aplurality of sensors spaced from the work wheel and the regulating wheelfor detecting at least the position of the workpiece during machiningoperations and for generating signals which correspond to the detectedposition of the workpiece. The slidable sensor bank is electivelyadjustable to a desired distance away from the work wheel and theregulating wheel to permit versatility in machining workpieces havingvarious lengths. The centerless grinder also includes processing meanscoupled to the plurality of sensors for processing the signals generatedupon detection of the workpiece, and for transmitting the processedsignals to effect desired movement of the regulating wheel, whereby adesired taper of the workpiece profile is obtained.

The centerless grinder may also comprise track means for guiding travelof the slidable sensor bank substantially parallel to the path of travelof the workpiece. In a preferred embodiment, the track means maycomprise an elongate T-shaped track.

The regulating wheel may be moved closer and further from the work wheelas required to produce the desired taper or diameter of the workpiece.The desired distance between the work wheel and the regulating wheel maybe defined as the sizing feature, which is the distance between the workwheel and the regulating wheel required to machine the workpiece to adesired diameter.

A slidable sensor bank is preferably mounted on the track means forslidable movement therealong. In one preferred embodiment, the slidablesensor bank may include at least one roller bearing assembly arrangedadjacent to the track means to facilitate selective slidable movement ofthe slidable sensor bank along the track means.

The plurality of sensors of the slidable sensor bank are preferablyarranged at a fixed position with respect to each other along the sensorbank. The sensors are preferably simultaneously movable as a group alongthe track means upon adjustment of the desired distance of the sensorbank from the sizing feature.

In a preferred embodiment, the centerless grinder comprises lockingmeans for selectively locking the slidable sensor bank at a desiredlocation on the track means. The locking means may comprise thecombination of a plurality of retaining holes arranged in the trackmeans spaced at predetermined distances from the sizing feature, and atleast one locking pin arranged on the slidable sensor bank. The lockingpin may be selectively movable from a locked position where it isarranged within a selected one of the plurality of retaining holes, andan unlocked position where it is remote from the associated retaininghole.

In a preferred embodiment, the support means for supporting theworkpiece during machining operations may comprise a work rest blade.The work rest blade may have a substantially horizontal supportingsurface, or may be arranged at an offset angle with respect to thehorizontal plane. The orientation of the support surface of the workrest blade may determine the profile of the machined workpiece.

The plurality of sensors may comprise photoelectric sensors. Thephotoelectric sensors may be spaced at various intervals along theslidable sensor bank. In one preferred embodiment where the slidablesensor bank is approximately thirty two inches long, photoelectricsensors may be arranged at 1/2 inch intervals. In another preferredembodiment, the photoelectric sensors may be arranged at 1/4 inchintervals. In alternative embodiments, the sensors may be ccd (changecoupled device) sensors, proximity sensors, inductive coupling sensors,magnetic sensing devices and various other types of sensors.

The slidable sensor bank is preferably mounted on an elongate T-shapedtrack which has a substantially horizontal top section and asubstantially vertical bottom section. Preferably, the slidable sensorbank is mounted on the top section of the track for selective slidablemovement therealong. The substantially vertical bottom section of theT-shaped track may include indicia for identifying predetermineddistances from the sizing feature.

The centerless grinder of the present invention may include means forfeeding the elongate workpiece to a desired location between the workwheel and the regulating wheel. These means may comprise cooperatingpinch rollers and a drive assembly for driving the cooperating pinchrollers.

The centerless grinder may also comprise workpiece retainer means forretaining the workpiece within a passageway during machining operations.The passageway should be large enough to permit the workpiece to rotateduring machining operations. The passageway should be small enough,however, to assure that the workpiece will remain detectable by theassociated sensors over its entire path of travel.

The workpiece retainer means preferably comprises an elongate retainermember which is controlled by an associated actuator. The actuator maybe a cylinder or the like which is pneumatically controlled,hydraulically controlled or mechanically controlled. In assembledposition, the retainer may be arranged substantially adjacent to a topsection of the slidable sensor bank.

Another aspect of the present invention pertains to a method of forminga passageway which is adapted to retain a workpiece during machiningoperations wherein the passageway has precise dimensions. The method inaccordance with this aspect of the present invention contemplates usingone or more micrometers to adjust the position of the workpiece retainerand to adjust the top section of the slidable sensor bank. One or bothof these components may be adjusted.

In a preferred embodiment of the present invention, the elongateworkpiece retainer and the top section of the slidable sensor bank aredisplaceable with respect to each other so that a precise passageway canbe formed in which the workpiece is arranged during machiningoperations. The elongate retainer and the adjustable top section of theslidable sensor bank may have cooperating ribs and grooves. To this end,the ribs may be arranged on one surface of the retainer while theadjustable top section of the slidable sensor bank may have groovesarranged in alignment with the ribs of the retainer so that the ribs ofthe retainer can be placed within the grooves of the adjustable topsection of the slidable sensor bank when these parts are in assembledposition. Conversely, the ribs may be arranged on the top section of theslidable sensor bank while the aligned grooves may be arranged on theretainer. This aspect of the present invention will permit thepassageway in which the workpiece is placed during machining operationsto be adjusted through a range of dimensions depending upon the size ofthe workpiece to be machined. At the same time, this arrangement willallow an additional workpiece to be retained in a temporary holdinglocation while another workpiece is being machined.

The passageway for placement of the workpiece during machiningoperations may be enclosed along substantially the entire length of theworkpiece. This preferred embodiment of the present invention permits aworkpiece to be retained for accurate detection by the plurality ofsensors arranged on the associated sensor bank.

In accordance with a preferred method of operating the presentcenterless grinder assembly, the ideal size dimensions and configurationof a perfectly machined workpiece are entered into the memory of acomputer system prior to beginning machining operations. A workpiece isthen placed within the passageway of the sensor bank assembly and thefirst machining run is performed. After the workpiece has been machinedto its desired configuration, it is fed through a gauging device whichaccurately measures all dimensions of the profile of the completedworkpiece. The information obtained by the gauging device iselectrically transmitted to the computer system and is compared with theideal dimensions of the completed workpiece which was entered into thecomputer memory prior to initiation of the machining process. Thecomputer system detects any deviation between the configuration of thecompleted workpiece and the ideal configuration which was previouslyinputted into the computer memory. Unless the profile of the firstmachined workpiece is exactly identical to the dimensions of the idealprofile, the computer system will send signals to a size control steppermotor or servo motor during machining of the next workpiece to create aworkpiece having a profile which is closer to the ideal profile than theprofile of the first machined workpiece. This is accomplished as thecomputer system sends signals to the size control stepper motor or servomotor which requires the regulating wheel to either move closer orfurther from the work wheel, or to move toward or away from the workwheel at a faster or slower rate so that precise constant diametersections and tapered sections can be obtained on the next machinedworkpiece. The centerless grinder assembly in accordance with thisaspect of the present invention may best be considered a "smart" systemas it learns from any machining errors which may have previously beenmade.

The first workpiece machined in accordance with the aforementionedmethod, and all subsequent machined workpieces, are obtained by assuminga feed rate for the workpiece while the position of the trailing end ofthe workpiece is continuously detected by photoelectric sensors. If anydeviation is detected between the first machined workpiece, orsubsequently machined workpieces, and the ideal profile which wasinitially entered into the memory of the computer system, compensationwill be obtained by control signals sent to the regulating wheel whichaffect the amount of movement and rate of movement of this wheelthroughout the grinding process with respect to the work wheel. Thiscompensation may include recalculating the assumed feed rate of theworkpiece as a function of this deviation.

Although an assumed feed rate of the workpiece is used in connectionwith preferred embodiments of the present invention, it should beappreciated that the feed rate of the workpiece may be an actualmeasured feed rate while remaining within the scope of the presentinvention.

An alternative preferred method of operating the present centerlessgrinder assembly incorporates various steps of the preferred methoddiscussed above. To this end, the ideal workpiece profile dimensions aredetermined prior to beginning machining operations and datarepresentative of such ideal profile dimensions are inputted into acomputer readable memory associated with the centerless grinderassembly. An elongate workpiece having a trailing end is then placed ata desired location on the centerless grinder assembly to be fed past aplurality of sensors and a work wheel during machining operations. Idealposition data is then determined which includes the desired position ofthe regulating wheel with respect to the work wheel of the centerlessgrinder assembly, and the corresponding position of the trailing end ofthe elongate workpiece with respect to the work wheel (or more preciselythe sizing feature of the work wheel). The ideal position data is theninputted into the computer readable memory. The elongate workpiece isfed past the plurality of sensors and the work wheel at a knownvelocity. This velocity may be an assumed velocity, or a measuredvelocity, so that an actual machined workpiece profile is obtained. Theposition of the trailing end of the workpiece with respect to the workwheel is continuously detected as it passes the plurality of sensors.The continuously detected positioned data is then converted into digitalsignals and is transmitted into the computer system. The actual positionof the regulating wheel with respect to the work wheel is alsocontinuously monitored and detected in correspondence with thecontinuous detection of the trailing end of the workpiece with respectto the work wheel. The continuously detected position data of thetrailing end of the workpiece, and the regulating wheel with respect tothe work wheel, are compared to the ideal position data to ascertaindeviations therebetween. Deviation signals are then generated whichrepresent the deviation between the continuously detected position dataand the ideal position data of the trailing end of the workpiece and theregulating wheel with respect to the work wheel. The deviation signalsare then transmitted to motor means for effecting movement of theregulating wheel closer to or further from the work wheel so that theactual machined workpiece profile will improve.

The step of continuously detecting the position of the trailing end ofthe workpiece with respect to the work wheel in accordance with thisalternative preferred method may comprise activating and initiating aclock each time that the trailing end of the workpiece is detected byone of the plurality of sensors. The estimated or actual position of thetrailing end of the workpiece between successive ones of the pluralityof sensors is then calculated by multiplying the elapsed time of theclock by the known velocity of the workpiece. Such calculations willpermit a relatively large sample of calculated or detected position dataof the trailing end of the workpiece with respect to the work wheel, andthe regulating wheel with respect to the work wheel, to be compared tothe ideal position data so that an accurate machined workpiece profilecan be obtained.

In accordance with this alternative method of operating a centerlessgrinder assembly, it is preferable to measure the dimensions along theprofile of the actual machined workpiece as discussed above and toperform the aforementioned steps associated with comparing the measureddimensions to ideal inputted workpiece dimensions so that the profile ofthe next workpiece to be machined will be at least as close to theinputted ideal workpiece profile as the previously machined workpiece.

Still another aspect of the present invention includes the use of theWINDOWS based operating system with a general purpose computer tocontrol an associated centerless grinding machine. The WINDOWS formatmachine control may vary in alternative embodiments. In a preferredembodiment, operator interface screens are provided which may include amain operating screen, a wire specifications screen, various taperspecifications screens, a paddle specifications screen, a wire set-upcontrol screen, a sizing control screen, a motor control screen, agauging screen, a machine calibration screen and a library back upscreen.

It is an object of the present invention to provide a centerless grinderwhich has the versatility to machine workpieces having a large range oflengths.

It is still another aspect of the present invention to provide a novelmethod of obtaining an accurate passageway within a centerless grinderto retain a workpiece during machining operations.

It is yet another aspect of the present invention to provide a method ofcontrolling a centerless grinder which utilizes a WINDOWS basedoperating system on a general purpose computer to control machiningoperations of elongate workpieces such as wires, rods, pins, golf clubshafts, and the like.

It is another object of the present invention to provide a simple methodof controlling a centerless grinder wherein precisely manufacturedworkpieces are obtained.

These and other objects, features and advantages of the presentinvention will be more readily understood when read in conjunction withthe following detailed description of the preferred embodiments and theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a centerless grinder system inaccordance with the present invention.

FIG. 2 is a partially broken away front view of a portion of a slidablesensor bank assembly in accordance with the present inventionillustrating roller bearings which facilitate slidable movement of thepresent sensor bank.

FIG. 3A is a partial sectional side view of the centerless grinderassembly of the present invention taken along line 3--3 illustrating theretainer bar in a closed position with respect to the top section of theslidable sensor bank.

FIG. 3B is a partial sectional side view of the centerless grinderassembly shown in FIG. 3A illustrating the retainer bar in an openposition with respect to the top section of the slidable sensor bank.

FIG. 4 is an exploded side view of the centerless grinder assembly shownin FIG. 3.

FIG. 5 is a bottom plan view of a T-bar on which the slidable sensorbank of the present centerless grinder is mounted.

FIG. 6 is an exploded isolated perspective view of selected componentsof the slidable sensor bank assembly illustrating the cooperating ribsand grooves of such components.

FIG. 7 is a schematic side view of selected components of the centerlessgrinder assembly of the present invention.

FIG. 8 is a top plan view of the combination of components shown in FIG.7.

FIG. 9 is a main operating screen created on a WINDOWS based operatingsystem in accordance with a method of operating the present centerlessgrinder.

FIG. 10 is a wire specifications screen created on a WINDOWS basedoperating system in accordance with a method of operating the presentcenterless grinder.

FIG. 11 is a loader control screen created on a WINDOWS based operatingsystem in accordance with a method of operating the present centerlessgrinder.

FIG. 12 is a sizing control screen created on a WINDOWS based operatingsystem in accordance with a method of operating the present centerlessgrinder.

FIG. 13 is a taper specification screen created on a WINDOWS basedoperating system in accordance with a method of operating the presentcenterless grinder.

FIG. 14 is a paddle specification screen created on a WINDOWS basedoperating system in accordance with a method of operating the presentcenterless grinder.

FIG. 15 is a wire set-up control screen created on a WINDOWS basedoperating system in accordance with a method of operating the presentcenterless grinder.

FIG. 16 is a main help screen created on a WINDOWS based operatingsystem in accordance with a method of operating the present centerlessgrinder.

FIG. 17 is a blade sizing help screen created on a WINDOWS basedoperating system in accordance with a method of operating the presentcenterless grinder.

FIG. 18 is a note pad screen created on a WINDOWS based operating systemin accordance with a method of operating the present centerless grinder.

FIG. 19 is a schematic view illustrating movement of a workpiece pastindividual sensors in accordance with a method of operating the presentcenterless grinder assembly.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A centerless grinder assembly 10 in accordance with a preferredembodiment of the present invention is illustrated in FIG. 1. Thecenterless grinder assembly 10 generally includes a computer system 12,a slidable sensor bank assembly 28 and a grinding assembly 14.

The computer system 12 may comprise a general purpose computer such as apersonal computer having a 486 based microprocessor and sufficientmemory to permit operation of the required software programs. Thecomputer system 12 includes a monitor for displaying operator interfacescreens generated by a WINDOWS based operating system. Preferredoperator interface screens in accordance with the present invention willbe discussed in detail below and are shown in FIGS. 9-15. The use of aWINDOWS based operating system to provide a user friendly operatorinterface environment is novel in the centerless grinder art.

The centerless grinder assembly 10 is preferably used to grind elongateworkpieces. By way of example, in describing the structure and operationof the present centerless grinder assembly 10, a wire 48 is discussedherein as a preferred elongate workpiece. However, it should beunderstood that the present centerless grinder assembly can be used tomachine an infinite variety of elongate workpieces other than wires,such as rods, pins, golf club shafts, etc.

As illustrated in FIGS. 1, 8 and 9, the grinding assembly 14 includes awork wheel 16 and a regulating wheel 18. The work wheel 16 is known inthe art and, in a preferred embodiment, may comprise a twelve inchdiameter grinding wheel. The regulating wheel 18 is also known in theart. In a preferred embodiment, it may have a diameter of about sixinches. A lead screw 22 and a precision stepping motor 20 may be used toselectively drive the regulating wheel 18 toward or away from the workwheel 16.

A work rest blade 24 is arranged between the work wheel 16 and theregulating wheel 18 for supporting the workpiece 48 during machiningoperations. The support surface 26 of the work rest blade 24 may behorizontally oriented, or it may be oriented at an angle with respect tothe horizontal plane as shown in FIG. 9. The angle of the work restblade support surface 26 will affect the overall orientation of themachined workpiece 48.

The slidable sensor bank assembly 28 is shown in a fully assembled statein FIG. 1. Various components of the slidable sensor bank assembly 28are shown in FIGS. 1-4 and 6.

As shown in FIGS. 1-4 and 6, the sensor bank assembly 28 includes afront end 30 and a rear end 32 with respect to the grinding assembly 14.The components of the sensor bank assembly 28 include an adjustable topsection 34 which has a slanted surface 36 with a plurality of grooves 38arranged therein. An elongate retainer bar having a slanted bottomsurface 42 with ribs 44 protruding therefrom is arranged adjacent to thetop section 34 when in assembled position. The ribs 44 of the elongateretainer member entered into aligned grooves 38 of the slanted surface36 of the top section 34 to provide an adjustable fitted arrangement asdiscussed further below. This aspect of the present invention is clearlyshown in FIG. 6.

A passageway 46 for retaining a workpiece 48 during machining operationsis formed between the elongate retainer bar 40 and the adjustable topsection as illustrated in FIGS. 3A-3B. The retainer bar 40 preferablyhas a plurality of ribs 44 extending along a slanted surface 42. Theadjustable top section 34 of the sensor bank assembly 28 preferably hascorresponding grooves 38 which extend within the slanted surface 36 andwhich are aligned with the ribs of the retainer bar 40. The cooperationbetween the ribs 44 of the retainer bar 40 and the grooves 38 of the topsection 34 of the sensor bank assembly 28 permit a relatively largerange of passageway dimensions to be formed for retaining various sizedworkpieces. The cooperating rib and groove arrangement is also usefulfor retaining an additional work piece to be machined in a holding area47 spaced from the formed passageway 46. This aspect of the presentinvention can be appreciated from the illustrations shown in FIGS. 3Aand 3B.

In a preferred embodiment, the retaining bar 40 is also adjustable.Adjustments of the top section 34 of the sensor bank assembly 28 and theretainer bar 40 may be performed along orthogonal Y and Z axes with oneor more micrometers 88 in accordance with the orientation of the Y and Zaxes depicted in FIG. 1. This will permit the formation of the workpiecepassageway 46 which has precisely determined dimensions. For example, ifthe centerless grinder assembly 10 is used to grind a workpiece 48 whichhas an initial constant diameter of 0.016 inch, it may be desirable touse micrometers 88 to adjust the top section 34 of the sensor bankassembly 28 and the retainer bar 40 so that the passageway 46 has adiameter of about 0.018 inch. The relationship between the size of thepassageway 46 and the workpiece 48 is clearly shown in FIG. 3.

The micrometers 88 may be removed after the desired adjustments of thetop section 34 and the retainer bar 40 of the sensor bank assembly 28have been performed.

The sensor bank assembly 28 includes a plurality of photoelectricsensors 68 which are adapted to detect at least the position of anassociated workpiece 48 during the machining process. The photoelectricsensors 68 are placed at predetermined intervals along the sensor bankassembly 28 for optical communication with a workpiece 48 arrangedwithin the passageway 46. Various types of known sensors are suitablefor use in accordance with the present invention. One preferred type ofsensor is a photoelectric sensors which is manufactured by KeyenceCompany. Such photoelectric sensors are well known in the opticalsensing art.

In one preferred embodiment, the slidable sensor bank assembly 28 may beabout thirty two inches long. The photoelectric sensors 68 may be placedat 1/2 inch or 1/4 inch intervals. In alternative embodiments, differentintervals may be selected for placement of the photoelectric sensors.Similarly, the length of the sensor bank assembly may also vary inalternative embodiments.

Pneumatically actuated devices 82 are coupled to the retainer bar 40 forselectively moving the retainer bar 40 between an open and a closedposition. The pneumatic actuators 82 include an air intake tube 84 and adischarge tube 86 which supplies the driving force for verticaldisplacement of the retainer bar 40. When the retainer bar 40 is in aclosed position as shown in FIG. 3A, the ribs 44 on the slanted surface42 are arranged within the grooves 38 of the slanted surface 36 on thetop section 34. Thus, the retainer bar 40 is substantially adjacent tothe adjustable top section 34 of the retainer. The passageway 46 forretaining the workpieces 48 is formed when the retainer bar 40 is in itsclosed position as indicated in FIG. 3A. When the retainer bar 40 is inan open position as shown in FIG. 3B, the ribs 44 are no longer withincorresponding grooves 38. The retainer bar is then remote from theadjustable top section 34 of the sensor bank assembly 28.

The slidable sensor bank assembly 28, including the adjustable topsection 34 and a retainer bar 40, is mounted for selectively adjustableslidable movement on a top surface 74 of a T-shaped support track 72.This aspect of the present invention is shown in FIGS. 1-4.

The distance between the work wheel 16 and the regulating wheel 18 whichis required to obtain a desired diameter at a location along theworkpiece 46 is known as the sizing feature. The T-shaped support track72 includes a substantially horizontal top section 74 and asubstantially vertical bottom section 76. Indicia 80, which representthe horizontal distance perpendicular from the sizing feature, arearranged at precise intervals along the substantially vertical bottomsection 76 of the T-shaped track 72.

The purpose of the marking indicia 80 is to identify the distancebetween the trailing end of the workpiece 48 and the sizing featureduring machining operations. The marking indicia 80 are also useful foradjusting the slidable sensor bank assembly 28 to a selected locationbased on the length of a workpiece 48 that will be machined. Since thephotoelectric sensors 68 detect the trailing end of the workpiece 48, itis important for the slidable sensor bank assembly 28 to be placed at asuitable location along the T-shaped track 72 such that thephotoelectric sensors 68 can detect the trailing end of the workpiece 48during the entire period that grinding occurs on the opposite end of theworkpiece.

The sensor bank assembly 28 is slidably adjustable along the top sectionof the T-shaped track 72 as it includes roller bearing assemblies 66arranged within recessed pocket areas 64 toward the front end 30 and therear end 32 of the sensor bank assembly 28. This aspect of the presentinvention is shown in FIG. 2.

As illustrated in FIG. 6, one side of the top section 74 of the T-shapedtrack 72 includes spaced holes 78 which serve as part of the lockingmeans of the present invention for selectively locking the slidablesensor bank assembly 28 in a desired position. The other portion of thelocking means is a locator pin 70 which is arranged at the bottomsection 62 of the slidable sensor bank assembly 28. The locator pin 70can be aligned with any of the holes 78 in the top section 74 of theT-shaped track 72. When the locator pin 70 is extended through aselected aligned hole 78 as shown in FIGS. 2, 3A and 3B, the sensor bankassembly 28 is arranged in a fixed position. Conversely, when thelocator pin 70 is pulled out of its assembled position within one of theholes 78, the sensor bank can slide along the T-shaped track 72 parallelto the x axis illustrated in FIG. 1.

As shown in FIGS. 3A, 3B and 4, the photoelectric sensors 68 are placedwithin the sensor bank assembly 28 through the rear side. Eachphotoelectric sensor 68 is arranged within a channel (unnumbered) andhas an unobstructed path for detecting the rear end of the workpiece 48as it is driven forward by the regulating wheel 18 along the passageway68 of the sensor bank assembly 28.

With reference to FIG. 1, the sensor bank assembly 28 includes a forwardend 30 and a rear end 28. The forward end 30 is arranged closer to thesizing feature of the work wheel 16 and the regulating wheel 18 than therear end 32. Thus, the marking indicia 80 arranged near the rear end 32of the sensor bank assembly 28 represents a greater distance from thesizing feature than the marking indicia 80 arranged closer to the frontend 30 of the sensor bank assembly 28.

As also shown in FIG. 1, various components other than the slidablesensor bank assembly 28 may be arranged on the T-shaped track 72. In apreferred embodiment, these additional components are also slidablealong the top section 74 of the T-shaped track 72 upon appropriateadjustment thereof. In particular, a wire guide 30 is arranged betweenthe front end 30 of the slidable sensor bank assembly 28 and thegrinding wheel 16. A bi-directional wire feeder and unloader 92 is shownin FIG. 1 between the front end 30 of the sensor bank assembly 28 andthe adjustable wire guide 90. The bi-directional wire feeder andunloader 92 may include a pinch roller assembly coupled with a drivemechanism for driving the pinch rollers. This aspect of the presentinvention is known in the centerless grinder art and has been used byRoyal Master Grinders, Inc. in various prior art centerless grinders.

The function of the bi-directional wire feeder and unloader 92 is tobring the front end 30 of the workpiece 48 to the regulating wheel 18 atthe start of the machining process and to then feed the completedworkpiece 48 back through the rear end 32 of the sensor bank assembly 28so that it can be unloaded after the machining process has beencompleted.

A second pinch roller assembly 94 for unloading machined workpieces 48can also be slidably arranged on the T-shaped track 72 near the rear end32 of the slidable sensor bank assembly 28.

A venturi wire unloader 96 is closely spaced from the pinch rollerassembly 94 near the rear end 32 of the sensor bank assembly 28 forfacilitating the removal of the completed workpiece 48. The venturi wireunloader 96 is connected to an unloader tube 98 through which theworkpiece 48 will be transported after the machining operations has beencompleted.

Various types of support mechanisms (not shown) may be employed tosupport the T-shaped track 72 and the slidable sensor bank assembly 28arranged thereon.

A wire 48 which has been machined to a desired configuration is shown inFIGS. 7 and 8 in a position between the work wheel 16 and the regulatingwheel 18. The completed profile includes a first substantially constantsmall diameter section 50 at the forward most end of the wire. Arelatively short tapered section 52 is arranged at the immediate distallocation to the constant small diameter section 50. An intermediateconstant diameter section 54 is formed in the central region of the wire48. The completed wire 48 also includes a second tapered section 56 anda relatively constant large diameter section 58 at the rear end. Thepresent centerless grinder 10 can be used to grind cylindrical partshaving numerous diameters and tapered sections. The completed workpiecescan be manufactured to extremely precise tolerances and may be providedwith low microfinishes. Various accurate profiles may be obtained.

As illustrated in FIG. 8, the work wheel 16 and the regulating wheel 18have angled surfaces which enable the workpiece 48 to be preciselymachined in accordance with the desired configuration. The regulatingwheel 18 is preferably arranged at a slightly offset angle with respectto a vertical plane (not shown). The offset relationship of theregulating wheel 18 with respect to the vertical plane is known in theart and permits the regulating wheel 18 to draw the workpiece 48 pastthe work wheel 16 while continuously spinning the workpiece 48. As isknown in the art, the vertical component of the regulating wheelorientation is primarily responsible for causing the workpiece 48 tospin while the horizontal component of the regulating wheel orientationis primarily responsible for drawing the workpiece 48 past the workwheel 16. Although the operation speeds of the regulating wheel 18 andthe work wheel 16 may vary, the regulating wheel 18 typically rotates atspeeds between 50-100 RPM while the work wheel 16 typically rotates atspeeds about 2000-2500 RPM.

FIG. 7 illustrates the workpiece 48 as it is supported on a work restblade 24. The work rest blade 24 includes a top support surface 26 whichmay be arranged at an offset angle with respect to a horizontal plane.The orientation of the support surface 26 of the work rest blade 24 mayvary depending upon the desired configuration of the workpiece 48. Thework rest blade 24 supports the workpiece 48 during the entire grindingprocess and permits the workpiece 48 to freely rotate on its top supportsurface 26 during the machining process.

In accordance with a preferred method of operating the presentcenterless grinder assembly 10, the ideal dimensions and configurationof a perfectly machined workpiece are entered into the memory of thecomputer system 12. A workpiece 48 is then placed within the passageway46 of the sensor bank assembly 28 and is drawn toward the work wheel 16by the front pinch roller assembly 90. The regulating wheel 18eventually grabs hold of the workpiece 48 and begins to draw theworkpiece 48 through the passageway 46 and past the work wheel 16.

The photoelectric sensors 68 continuously detect the trailing end of theworkpiece 48 as it passes the sensors. Signals are generated by thephotoelectric sensors 68 which correspond to the passage of the trailingend of the workpiece 48. The signals are then processed by the computersystem 12, and computer system 12 transmits corresponding controlsignals to the size control stepper or servo motor 20 of the regulatingwheel 18. The size control stepper or servo motor 20 actuates a leadscrew 22 to cause the regulating wheel 18 to move toward or away fromthe work wheel 16 depending upon the amount of stock to be removed fromthe workpiece 48.

After the workpiece 48 has been machined to its desired configuration,the front pinch roller assembly 90 is activated to grab the workpiece 48and feed it toward the rear end 32 of the sensor bank assembly 28. Thecompleted workpiece 48 is then grabbed by the pinch roller assembly 94located near the rear end of the sensor bank assembly 28 which feeds theworkpiece 48 through the venturi unloader 96 and into the unloader tube98 which delivers the completed workpiece 48 to a receiving tray.

In order to determine the accuracy of the dimensions and profile of theworkpiece 48 after grinding is completed, the workpiece 48 is fedthrough a gauging device which may be arranged within the pinch rollerassembly 94.

Alternatively, the gauging device may be arranged between the pinchroller assembly 94 and the venturi unloader 96 or at various otherlocations. The gauging device accurately measures the dimensions of theentire profile of the completed workpiece 48. The information obtainedby the gauging device is electrically transmitted to the computer system12 and is compared to the ideal dimensions of the completed workpiecewhich were entered into the computer memory prior to initiation of themachining process. The computer system 12 will detect any deviationbetween the configuration of the completed workpiece 48 and the idealconfiguration which it retains in its memory. These dimensionaldifferences can vary with respect to the constant diameter sections 50,54 and 58, and the tapered sections 52 and 56 of the workpiece 48.

In a preferred embodiment of the present invention, workpiece 48 isautomatically fed through the gauging device after grinding operationshave been completed. Further, in alternative embodiments, the workpiece48 may be manually placed in the gauging device. In the manualembodiment, the gauging device may be remotely arranged with respect tothe sensor bank assembly 28. However, the gauging device will preferablyremain electrically connected to the computer system 12 so that thedimensions of the workpiece profile, which have been measured by thegauging device, are electrically transmitted to the computer system 12as discussed above. In yet another embodiment, the gauging device maynot be electrically connected to the computer system. To this end, themeasured dimensions may be manually inputted into the computer by akeyboard, or the like.

One gauging device which is suitable for use with the present inventionis presently manufactured by Royal Master Grinders, Inc., the assigneehereof, and is commercially available as Royal Master Grinders Model No.SA910. Such a gauging device utilizes a transducer to measure thediameter of the workpiece. The transducer may be a pneumaticallyactuated LVDT (linear variable differential transformer) having asufficient stroke to clear the workpiece 48 and sufficient accuracy andrepeatability to assure diameter measurements within desired tolerances.Royal Master Grinders Model No. SA910 gauging device utilizes an LVDTwith low force actuation and sufficient stroke (±0.10 inch) and accuracy(0.00005 inch) or better.

This gauging device creates an electronic signal proportional to thetransducer position. A special tip is provided that works in cooperationwith a matching anvil so that the wire surface and shape is not alteredor damaged during gauging operations.

The aforementioned gauging device is particularly useful to detect theprofile and dimensions of a workpiece 48 when the workpiece is manuallyplaced within the gauging device. To this end, the workpiece 48 isattached to a linearly moving element which causes an electrical signalto be generated according to the workpiece position. Thus, the diameterand length of the workpiece are continuously referenced to each other asits profile is accurately determined.

Other means to measure the workpiece diameter to best determine itsprofile may include a non-contact device such as a laser micrometerwhich generates a usable electronic signal which can be processed by anappropriate algorithm to compute the profile of an associated workpiece.As the present invention is not limited to a particular type of gaugingdevice, it should be understood that various gauging devices which mayinclude existing or future technology may be used to measure thedimensions of a workpiece.

Present means of moving the workpiece 48 in an embodiment where thegauging device is remote from the sensor bank assembly 28 includes a setof clips with a potentiometer which are assembled and mounted on a smallplatform. This platform assembly is slidable on a track which may besimilar to the T-shaped track 72, and which is arranged in line with themeans for measuring the workpiece diameter, such as the LVDT device.Other means of moving the workpiece 48 may be utilized such as linearstepper motors or rotary pinch rollers in conjunction with stepper motoror the like.

In order to compensate for differences in the constant diameter sectionswhen the next workpiece is machined, the computer will direct the sizecontrol stepper or servo motor 20 to activate the lead screw 22 so thatthe regulating wheel 18 moves closer or further from the work wheel 16,or initiates such movements at a later or earlier time, when the nextworkpiece is machined. Thus, the sizing feature will be adjusted in aneffort to obtain the ideal constant diameter parameters which werepreviously inputted into the memory of the computer system 12. In orderto correct deviations between the actual tapered sections 52 and 56 andthe ideal configuration of the tapered sections, the computer system 12will send appropriate signals to the size control stepper or servo motor20 to activate the lead screw 22 so that the regulating wheel 18 will bemoved toward or away from the work wheel 16 at a faster or slower rate,or such that such movements begin at a later or earlier time, when thenext workpiece is machined. The computer system 12 also may adjust, as afunction of these differences, the assumed feed rate for the workpiecefor executing the grinding profile.

As can be appreciated from the aforementioned discussion of the novelmethod of operating the centerless grinder assembly 10, the presentsystem is a "smart system", as it creates workpieces having increasinglymore accurate profiles as a result of learning of the minor variationsin the profile of workpieces 48 with respect to the previously inputtedideal workpiece profile.

A further alternative method of operating a centerless grinder assemblywill now be described with reference to FIG. 19 which schematicallyillustrates the workpiece 48 as it passes various photoelectric sensors68 of the present centerless grinder assembly 10. The initial steps ofthis alternative method are similar to that discussed above. Inparticular, the ideal dimensions and configuration of a perfectlymachined workpiece are first entered into the memory of a computersystem 12. The workpiece 48 is then placed within the passageway 46 ofthe sensor bank assembly 28. The front pinch roller assembly 90 is thenactivated to feed the front end of the workpiece 48 toward the workwheel 16 and the regulating wheel 18. When the regulating wheel 18eventually grabs hold of the workpiece 48, the front pinch rollerassembly 90 will be deactivated and the regulating wheel 18 will drawthe workpiece 48 through the passageway 46 and past the work wheel 16 tobegin the grinding process.

Referring to FIG. 19, the position of the trailing end E of theworkpiece 48 is continuously monitored by the individual photoelectricsensors 68. For ease of reference, each of the photoelectric sensors 68are separately identified in FIG. 19 by reference letters and numeralsS1 through S64.

As discussed above, movement of the regulating wheel 18 will effect theprofile of the workpiece 48. For example, as the regulating wheel 18 ismoved toward the work wheel 16, additional stock is removed from theworkpiece 48 during grinding operations. Conversely, as the regulatingwheel 18 is moved away from the work wheel 16, less stock is removedfrom the workpiece 48. A tapered profile will be obtained when thesizing feature is modified during grinding operations by movement of theposition of the regulating wheel 18 with respect to the work wheel 16.

As in Royal Master Grinders' prior art centerless grinder guide wiresystems, and as in the preferred embodiments of the present inventiondiscussed above, sensors (not shown) are placed in association with theregulating wheel 18 and the stepper motor 20 for providing signals tothe computer system 12 to identify the position of the regulating wheel18 with respect to the work wheel 16 during the grinding process. Asdiscussed above, activation of the stepper motor 20 and the lead screw22 will adjust the position of the regulating wheel 18 and the rate ofmovement thereof toward or away from the work wheel 16.

The feed rate (i.e., the velocity) at which the workpiece 48 will bedrawn past the work wheel 16 by the regulating wheel 18 will preferablybe an assumed calculated value when performing this alternative methodof operating the present centerless grinder assembly 10. It should beappreciated, however, that the feed rate of the workpiece 48 can also bea measured value, and need not be an assumed calculated value. Thevelocity of the workpiece 48 will be based on various factors known inthe art, such as the RPM's, tilt angle and diameter of the regulatingwheel.

When an assumed calculated workpiece feed rate is used, it may bedetermined in accordance with the following equation:

    V(velocity of the workpiece)=k×D(diameter of the regulating wheel)×RPM(regulating wheel)×tan of regulating wheel tilt angle.

The parameter k=k_(o) ×k_(i), where k_(o) is a constant (Π/60) and K_(i)is a slip variable related to variations in the feed rate of theworkpiece under certain grinding conditions. For instance, k_(i) mayvary depending upon factors such as the diameter of the workpiece 48prior to grinding, the instantaneous wire diameter during grinding, theshape of the template, the coefficient of friction of various componentsincluding the regulating wheel 16, the work wheel 18 and the work restblade 24. A non-slip condition is obtained in an ideal environment sothat k_(i) =1. Accordingly, an ideal value of k=Π/60. However, underactual conditions a slip variable will come into play. The slip variablek_(i) will typically have a value of 0.60-200, although lower and higherslip variable values may exist. Thus, k will typically have a valuebetween (0.6 Π)/60 abd (2.0×Π)/60. The feed rate (i.e., velocity) of theworkpiece 48 may typically be about 1.1 inches/sec., although much loweror greater feed rates may be used. Such a typical feed rate will beobtained when the regulating wheel diameter D=6.0 inches, the regulatingwheel RPM's=100 rev/min, and the regulating wheel tilt angle=2°.

As the trailing end E of the workpiece 48 continues to travel toward theregulating wheel 18 and the work wheel 16 along the X axis of the sensorbank assembly 28 (see FIG. 1) the position of the trailing end E will bedetected by the successively arranged photoelectric sensors 68 (s1-S64)and electrical signals will be transmitted to the computer system 12 tobe digitally processed. The position of the trailing end E of theworkpiece 48 will be continuously monitored by the photoelectric sensors68.

An internal clock (not shown) of the computer system is associated withthe photoelectric sensors 68 for calculating an estimated, or actual,position of the trailing end E of the workpiece 48 along the path oftravel. The internal clock may be initialized each time that thetrailing end E of the workpiece 48 is detected by a sensor 68. When thetrailing end E of the workpiece 48 is located between successive sensors68, the computer system 12 will calculate the position of the trailingend E of the workpiece 48 based on the elapsed time of the internalclock and the known (either estimated, calculated or actual) feed rateof the workpiece.

For example, the position of the trailing end E of the workpiece 48between sensor S1 and S2 is calculated by the computer which utilizes aformula to multiply the known feed rate of the workpiece 48 by theelapsed time that expired after the trailing end E was initiallydetected by sensor S1. The calculated position represents the positionthat the trailing end E of the workpiece 48 is spaced from the sizingfeature when the calculation is performed. If an estimated feed rate isused, the calculated position will be an estimated position based onmultiplication of the estimated feed rate and the elapsed time fromdetection of the trailing end E. In accordance with this aspect of thepresent invention, the originally estimated feed rate need not berecalculated at any time during machining operations.

The computer will continuously monitor the trailing end E of theworkpiece 48 at a known interval, such as about every thirtymilliseconds. This interval may vary substantially in alternativeembodiments of the present invention. It should therefore be appreciatedthat the quantity of position calculations performed by the computerwill vary in inverse proportion to the time of the sampling interval.This sampling interval will also be used to determine the frequency thatposition data detected by the sensors (not shown) associated with theregulating wheel will be transmitted to the computer to establishcorresponding data regarding the position of the regulating wheel 18with respect to the work wheel 16. Accordingly, the two sets of data(i.e., the data representing the distance between the trailing end E ofthe workpiece and the sizing feature, and the distance between theregulating wheel and the work wheel) are obtained at precisely the sametime.

In addition to the ideal profile dimensions of the workpiece 48, whichhave been inputted into the computer memory, the computer ispreprogrammed to include a formula, or a table (known as a "look-uptable") which provides the position that the regulating wheel 18 shouldbe at with respect to the work wheel 16 in order for the workpiece 48 tobe machined to the desired profile when the trailing end E of theworkpiece 48 is in a known location (i.e. a location at a known distancefrom the sizing feature).

The computer will continuously process each of the signals transmittedby the successive sensors 68 which represents the position of thetrailing end E of the workpiece 48 with respect to the sizing feature.When a greater sample size is desired the computer will continuouslycalculate the position of a trailing end E of the workpiece 48 when itis located between successive sensors 68. To this end, the computersystem 12 will calculate the position of the trailing end E of theworkpiece 48 based on the elapsed time of the internal clock and theknown feed rate of the workpiece. As discussed above, this calculationmay be obtained by multiplying the known feed rate of the workpiece bythe elapsed time that expired after the trailing end E was detected bythe immediate preceding sensor 68. The computer will also continuouslyreceive signals detected by the regulating wheel sensors which willprovide information as to where the regulating wheel 18 is with respectto the work wheel 16 at a point in time that corresponds with a knownposition of the trailing end E of the workpiece 48 from the sizingfeature. As discussed above, such continuous monitoring of the trailingend E of the workpiece 48 and the relative position of the regulatingwheel 18 with respect to the work wheel 16 may occur at various selectedintervals such as about every 30 milliseconds.

The computer will compare the data regarding the continuously detectedposition of the workpiece 48, and the measured regulating wheelposition, to the proper location of the regulating wheel 18 asdetermined by the data of the look-up table. If the regulating wheel 18is at an appropriate location with respect to the work wheel 16 toobtain the desired profile in accordance with the ideal workpieceprofile dimensions which were previously inputted into the computersystem memory, no compensation signals will be sent to the regulatingwheel. However, if the computer determines that the position of theregulating wheel needs to be adjusted at a particular time in order tocomply with the look-up table data, appropriate signals willautomatically be sent to the stepper motor 20 by the computer to causemovement of the regulating wheel 18 toward or away from the work wheel16 as quickly as possible.

As with the previously described preferred embodiment of the presentinvention, the workpiece 48 may be drawn through a gauging device aftergrinding operations have been completed. The gauging device will measurethe actual dimensions of the workpiece profile. To this end, theworkpiece 48 may be automatically or manually fed through the gaugingdevice and the measured profile dimensions may be automatically ormanually entered into the computer system 12. If differences existbetween the actual dimensions of the ground workpiece 48 and thedimensions of the ideal workpiece profile as previously inputted intothe computer memory, the formula, or the data in the look-up table, willbe recalculated so that machining of the next workpiece will result inan overall profile that is closer to the ideal workpiece profile thanthe previously machined workpiece.

Alternatively, the assumed feed rate calculation may be modified to moreclosely approximate the actual feed rate so that an improved workpieceprofile can be obtained. Still further, the feed rate of the workpiece48 can be selectively increased or decreased during the next machiningrun so that the position of the trailing end E of the workpiece willcorrespond with the proper position of the regulating wheel 18 withrespect to the work wheel 16 at selected points in time. If the feedrate of the workpiece is increased as discussed above, it may not benecessary to modify the look-up table to obtain an overall workpieceprofile that approximates the ideal workpiece profile.

The aforementioned alternative method of operating the centerlessgrinder assembly 10 is therefore based on continuously monitoring theposition of the trailing end E of the workpiece 48 by the fixedphotoelectric sensors 68 and/or calculating the position of the trailingend E between successive sensors 68 based on a known feed rate and theinterval clock values.

While the workpiece 48 is being machined, the next workpiece to bemachined may be placed in a holding area 68 formed between the retainerbar 40 and the top section 34 of the sensor bank assembly 28. Thisaspect of the present invention is shown in FIGS. 1, 3A and 4. While theworkpiece 48 is being machined by the work wheel 18 and the regulatingwheel 16, it will be retained within the continuous passageway 46 formedbetween the retainer bar 40 and the top section 34 of the sensor bankassembly 28. At this time, the relationship between the closedpassageway 46 and the workpiece 48 will appear as shown in FIG. 3A.

After the workpiece 48 has been machined to a desired configuration, itis drawn out of the passageway 48 as discussed above. At this time, thepneumatically controlled actuators 82 are activated to pull the retainerbar 40 to an open position with respect to the top section 34 of thesensor bank assembly 28 as shown in FIG. 3B. The next workpiece to bemachined which was previously retained in the holding location 60between the retainer bar 40 and the top section 34 of the sensor bankassembly 28 automatically falls into the passageway 48 when the retainerbar 40 is pulled to its opened position. The retainer bar 40 is thenreturned to a closed position to again form a precisely sized passageway46 to retain the workpiece 48 during machining operations.

The slidable sensor bank assembly 28 of the present centerless grinderassembly 10 is particularly useful when an unusually long workpiece isto be machined. To this end, the slidable sensor bank assembly 28 can bequickly and precisely moved to a further location along the X axis withrespect to the sizing feature. This can be accomplished by firstadjusting the position of the venturi unloader 96 and the wire unloaderpinch roller assembly 94. The locator pin 70 of the sensor bank assembly28 should then be removed from its assembled position within one of theholes 78 in the top section 74 of the X axis of the T-shaped track 72.The sensor bank assembly 28 is then free to slide along the T-shapedtrack 72 until it is placed at a desired location where thephotoelectric sensors 68 can continuously detect the trailing end of theworkpiece during machining operations. It may be necessary totemporarily disconnect some or all of the photoelectric sensors 68 fromthe sensor bank assembly 28 or from an associated processing unit whilethe sensor bank assembly 28 slides to the desired final position on theT-shaped track 72. The photoelectric sensors 68 should then bereconnected as necessary. In a preferred embodiment however, it is notrequired to disconnect any of the photoelectric sensors 68 duringmovement of the sensor bank assembly 28.

In an alternative embodiment, the pinch roller assembly 94 and theventuri inloader 96 can be integral with the sensor bank assembly 28. Insuch an embodiment, removal of a single locator pin from an aligned holein the T-shaped track will permit simultaneous slidable movement of thephotoelectric sensors, the pinch roller assembly and the venturiunloader.

The present method of operating a centerless grinder assembly 10provides various advantages over prior art methods. One such advantageis obtained through the WINDOWS based operating system which has beenimplemented to provide simple operating procedures through the generalpurpose computer system 12. FIGS. 9-18 illustrate ten preferred screenswhich can be accessed through the WINDOWS based operating systems of thepresent invention. These screens make the operating procedures userfriendly so that an operator is unlikely to make an error.

The program for creating the customized user friendly screens shown inFIGS. 9-18 will be automatically loaded after an operator turns on themain power switch of the computer system 12. Information screens will bedisplayed indicating progress of the program as it is being loaded.After the loading procedure is completed, the main operating screenshown in FIG. 9 will automatically appear on the monitor.

The main operating screen functions as a cockpit and enables theoperator to input essential information and access additional controlscreens. The operator can use a mouse or track ball to position thecursor over the desired control function. Typically, the left button onthe mouse should be clicked to actuate a desired function after thecursor has been positioned.

The main operating screen shown in FIG. 9 will permit an operator toturn the grinder spindle on or off. The spindle state will be shown inthe button window. The system hydraulics and the coolant can also beturned on or off by positioning the cursor and clicking at theappropriate button window shown in FIG. 9. The hydraulic and coolantflow state will also be shown in the appropriate button window. Thecoolant flow can also be turned to "grind" or "dress".

The grind cycle can be started or stopped at the completion of a cycle.The main operating screen also permits the operator to immediately abortthe grind cycle with the "quick release" command. The state of the grindcycle is scrolled in the "cycle status" message window while the grindcycle is being performed. The information provided indicates the variouscycle states such as "ready, feeding, grinding, diameter #1, 2, 3, etc.,grinding taper #1, 2, 3, etc., clear unloading", and other grind cycleinformation.

The regulating wheel RPM's are monitored and displayed in the mainoperating screen. The main operating screen also permits other functionssuch as counters and "spindle load" to be adjusted.

The "Ram Position" is displayed in a bar form with the correspondingnumber of inches or millimeters representing the size of the gap betweenthe wheels (the resulting part size). The up/down scroll arrows permittrim adjustment of the readout bar and corresponding number. This is adynamic measurement.

The main operating screen also displays the "wire position" as inches ormillimeters from the distal end of the wire. The wire position is alsodisplayed with respect to the location of its trailing end within theeyebar (i.e., sensor bank). The sensor state of each individual sensorin the eyebar is also displayed. This information is useful to confirmthe satisfactory operation of all of the photoelectric sensors 68.

The actual spindle load is displayed and the "trip point" can be set tostop the machining process immediately if conditions resulting in anincrease in motor load should occur in excess of the set maximum loadpoint.

The main operating screen also includes gauging counter controls whichset the number of parts to be ground until gauging is required. The partcount is displayed and when the preset number is reached, the automaticcycle goes on hold until the operator resets the function. The cyclecounter control on the main operating screen permits an operator to setthe number of parts which will be ground in a particular lot. The partcount is displayed and when the preset number is reached, the automaticcycle goes on hold until the operator resets the function.

The WINDOWS menu bar located at the top of the main operating screenwill permit the operator to select additional screens required to inputor verify necessary information.

FIG. 10 illustrates the "wire specifications screen" which can beaccessed by clicking on the "wire" entry of the menu bar located at thetop of the main operating screen. After the wire specifications screenis displayed, the operator should click the mouse on the "part #" pulldown arrow. The mouse should then be used to select a part from thelist. Information for the selected part will be displayed in the variousinformation boxes.

Various windows have spin dials and pull down menus. The spin dials areused to change a value such as diameter or length. Pull down menus areused to select a choice item or type a new choice from which to select.

New parts can be entered entirely or copied from existing selections andchanged. They are assigned new numbers or names by typing in theappropriate window. Existing parts can be deleted from the choices withthe "delete" button. The regulating wheel RPM speed can be entered. TheRPM information is used in calculating the assumed wire speed.

Information in the wire specifications screen can be saved or abortedupon exiting back to the main operating screen.

The wire specifications screen permits an operator to access the "taperspecifications screen" shown in FIG. 13. This can be accomplished byclicking on the "tapers" button. The taper specifications screen permitsthe operator to view the set parameters or change information about theworkpiece tapers or profile shape. When the taper specifications screendisplays appropriate information, the operator should click on thesave/exit button. Once the operator exists the taper specificationsscreen, the wire specifications screen is again displayed beforereturning to the main operating screen.

Each tapered section has its own dedicated screen. For example, thediameter and length of the tapered sections 52 and 56 of the workpiece48 has its own screen as shown in FIG. 13 for inputting requiredinformation to obtain the desired taper profile. The end diameter oftapered section 52 should be the same as the start diameter of taperedsection 56.

As indicated on FIG. 13, the WINDOWS screen includes a prompt for thestart and end diameters of a desired taper length. The start diameter oftapered section 56 cannot begin before the end diameter of taperedsection 52. The operating program acknowledges this requirement and thusinteracts between the screens.

The differential between the start and end diameters is computed by theprogram and is continuously displayed in a taper specifications screenas "diameter differential". This differential may be positive ornegative depending on whether an increase or a decrease in diameter isdesired.

As shown in FIG. 13, the taper specifications screen also includesprompts for inputting a start distance and the end distance of eachparticular taper, such as tapered sections 52 and 56. After the startand end taper distances have been inputted, the program willautomatically calculate the taper length and will display such length onthe taper specifications screen.

A taper number display indicates the taper number and has a spin wheelto change to an adjacent taper. The units may be optionally displayed ininches, millimeters or centimeters as set in the wire specificationsscreen. Each taper specifications screen has a button to abort or tosave the data and to then exit to the wire specifications screen.

FIG. 14 illustrates the paddle specifications screen which includesprompts to receive and display information in a manner similar to theaforementioned discussion of the taper specifications screen. The paddlespecifications screen has data windows and adjustment means such as spinwheels, fast and slow, etc. to adjust the values adjacent to the data.

The paddle specifications screen includes prompts for entering thepaddle diameter and the neck diameter as well as a differential amount.Each of these values are independently entered. The differential iscontinuously computed and displayed. It is also adjustable and isconnected to the two diameters so that the neck diameter may be adjustedaccording to the amount of the differential set.

A prompt is also provided for inputting the paddle length. Thisdimension is calculated from the outer edge of the work wheel 16. Eachof the aforementioned dimensions has an offset value data window whichcan be set in accordance with desired tolerances.

A set point may be provided between the paddle diameter and the neckdiameter at which point the paddle grinding retention unit is releasedjust before the neck diameter is reached. This allows very small neckdiameters to be ground without undercuts. The device allows linearmotion of a workpiece to resume which is also a smooth transition to theneck diameter. The release point is expressed in terms of diameter aswell as a percentage of the difference of the two diameters. Thecomputation of this data also includes the offset of the diameters.

Panel specification units will be displayed in inches, millimeters orcentimeters. Such units may be selected in the wire specificationsscreen. The paddle specifications screen of FIG. 14 also includes abutton to abort or to save the data and to then exit to the wirespecifications screen.

FIG. 15 illustrates a wire set-up control screen which displays thelocation of the trailing end of the workpiece 48 as a function of itsposition with respect to the plurality of sensors 68 of the sensor bankassembly 28. The wire set-up control screen allows the system operatorto manually check all of the machine and loader functions. Solenoidcontrol buttons are provided for permitting an operator to controlmovement of the retainer bar 40 between an open and a closed position.As discussed above, the retainer bar 40 is shown in its closed andopened positions in FIGS. 3A and 3B, respectively. Proper control overthe retainer bar 40 is important to set the required dimensions of thepassageway 46 between the top section 34 and the retainer bar 40 of thesensor bank assembly 28.

When the passageway 46 is empty (i.e., when no workpiece is arrangedtherein), a test workpiece is placed in the holding location 60 betweenthe retainer bar 40 and the top section 34. The retainer bar 40 is thenmoved to the open position of FIG. 3B by clicking on the wire retainerbutton. The test workpiece will drop into the passageway 46 and the wireposition indicator bar of the wire set-up control screen will changecolors indicating that each of the photoelectric sensors 68 has detectedthe presence of the workpiece. The retainer bar 40 should then be movedto its closed position of FIG. 3A by clicking the appropriate buttoncontrol.

Calibration of the sensor bank assembly 28 may be performed from thewire set-up control screen. For example, refer to FIG. 15. To this end,an operator should click on the Wire Sensor Calibration box and followthe prompts. The operator is prompted to place a wire in the holdinglocation 60 between the retainer bar 40 and the top section 34 of thesensor bank assembly 28, and click again. The retainer bar 40 moves toan open position as shown in FIG. 3B and the wire workpiece 48 dropsinto the passageway 28. The operator observes that the red screen bardisplay changes to green, indicating that the individual sensors 68 arecovered by the wire 48. The operator is further prompted to click againand the retainer bar 40 moves to a closed position as shown in FIG. 3A.The operator is then prompted to adjust the sensor bank assembly 28 sothat the wire moves and spins freely by hand. With all sensors 68covered, the operator is further prompted to click again indicating thatthis operation hs been performed, and all of the sensor assemblyamplifiers are set to the calibrate mode. Each of the individual sensors68 have yellow LEDs which light. The operator is prompted to remove thewire workpiece 48 from the sensor assembly 28 and click again, toindicate that this operation has been performed. The operator observesthat the green screen bar display changes from green to red, indiciatingthat the individual sensors 68 are uncovered by the wire 48 and theamplifiers are then reset to normal. Each of the red LEDs associatedwith the individual sensors 68 are lit and the operator is prompted thatthe calibration procedure is completed.

The general procedure is to place a workpiece 48 within the passageway68 as discussed above so that all of the photoelectric sensors 68 detectthe presence of the workpiece 48. The operator should then click on thebutton which starts the amplifiers of the photoelectric sensors 68 toadjust the electronic gain of each and to simultaneously detect thepresence of the workpiece 48. The workpiece 48 may then be removed fromthe passageway 46 of the sensor bank 28. When the operator clicks on theappropriate button, the amplifiers of the photoelectric sensor 68 willbe simultaneously set to disregard any background object beyond theworkpiece 48. This operating procedure is unique to the centerlessgrinding field.

The pinch roller assemblies 92 and 94 can be activated by clicking onthe "wire grips" button. The feeder motors of the pinch rollerassemblies 92 and 94 can then be operated to move the workpiece 48 alongthe x axis toward or away from the work wheel 16 and the regulatingwheel 18 by clicking on the "reverse" or "forward" buttons which controlthe wire feed motors. The individual sensor indicators of the indicatorbar at the top of the wire set-up controls screen will successive changecolors to denote detection of workpiece movement by the photoelectricsensors 68 so that an operator can evaluate the performance of theindividual, photoelectric sensors 68 as desired.

The unloader venturi 96 can also be controlled by clicking on theappropriate button of the wire set-up control screen. Additionally, theoperator may set the wire shifter by clicking on the appropriate button.The aforementioned functions are generally needed to set up a newinstallation check and to adjust various settings including thepneumatic connections of the control actuators 82, the flow valvesettings, the dimensions of the passageway 46, and additional mechanicalclearances.

When all desired functions have been performed, the operator can exitthe wire set-up control screen by clicking on the save and exit button.The system would then return to the main operating screen of FIG. 9.

The operator may elect the loader control screen of FIG. 11 from themain menu bar of the main operating screen. The loader control screenwill permit the operator to set the parameters that are associated withloading of a workpiece 48, unloading workpiece 48 after machiningoperations have been completed, setting of the location of the sensorbank 28, setting of the manual jog speed, and setting the offset of thewheel dressing template location.

The sensor bank location is set with the spin wheels. Preferably, thelocation data is displayed in both inches and centimeters. The operatormay set this to the location of the locating pin 70. The program willautomatically calculate and display the recommended location just belowthe actual set location. This will allow the operator to have somediscretion in selecting the actual location, while providing theoperator with guidance as to the recommended location.

During the wire loading cycle, the pinch roller assemblies feed theworkpiece 48 at the set feed rate until the release position is reached.This is the point where the regulating wheel 18 will cause the workpiece48 to spin and grinding by the work wheel 16 will commence. The computerwill calculate the position of the workpiece 48 based on variousinformation which may include the workpiece diameter, the tip or paddlediameter, and the angle of the dressing template used. Other informationmay be used by the computer to calculate the workpiece position.

The operator may select either an automatic or a manual unload cycle byclicking on the appropriate button of the loader control screen. If anautomatic load cycle is selected, the operator may then selectadditional parameters including the wire feed speed and the venturidwell time.

This will allow for complete passage of the workpiece 48 past theunloaded sensor before ending the cycle. If a manual load is selected,the operator will not be permitted to set certain data. This data willbe "grayed" out visually on the loader control screen and should beignored by the operator.

The manual jog values may also be set by the operator in this screen.The ram can be manually jogged--either fast or slow and displayed ininches per second or millimeters per second. These values are used atcertain times during the automatic grinding cycle. The "wire feed high"and "wire feed low" settings are only needed in the manual mode.

The template offset window allows the operator to compensate all linearlength dimensional data for the actual size features of the actual wheelconfiguration as a result of slight template deviations from the idealdesign.

The data initially displayed in the loader control screen is loaded fromthe library of stored part numbers. If no information regarding thestored part numbers exists in the library, default data will bedisplayed. This data can be adjusted as described above. The operatormay exit the loader control screen by clicking on the abort/exit buttonor by clicking on the save/exit button, which will save all of the datato a file associated with the part number selected. In either case, thesystem will return to the main operating screen.

The operator may gain access to the "sizing control" screen by clickingon the sizing prompt from the main menu bar of the main control screen.The sizing control screen is shown in FIG. 12. The initial datadisplayed in the sizing control screen is loaded from the library of thepart previously selected.

The top portion of the sizing control screen provides buttons forcontrolling the machine spindle motor and the coolant flow. The spindleload and trip point are displayed and set to the same values as set inthe main operating screen. The regulating wheel speed (in RPMs) and theram position is also displayed. The regulating wheel speed will be thesame as the regulating wheel speed displayed in the main operatingscreen.

The jog mode area may be used by the operator to position the regulatingwheel 18 in close proximity to the work rest support blade 24. Variousspeed values can be selected in terms of inches per second ormillimeters per second.

The decrease and increase buttons displayed in the "incremental move"section of the sizing control screen will allow the operator to move theregulating wheel 18 as close to the work rest blade 24 desired. Theincremental mode can be set for very accurate small amounts of motionsuch as 0.00010 inch.

Straps which connect the ram to the blade should be tightened after thedesired sizing feature is obtained. The ram and the work rest blade 24are then "jogged" together as a unit until they are in close proximityto the work wheel 16. The ram and the work rest blade 24 may thenincrementally moved together as a unit until they touch the work wheel16.

When the work rest blade 24 is ready for sizing, the coolant is turnedon to "grind". During the sizing routine, the work rest blade 24 willadvance into the work wheel 16. It will hold for a dwell time, and willthen retract away from the work wheel by an amount set in the "pecking"distance. The pecking distance is the amount of retraction after thesize dwell. This distance may be set to any positive value. A typicalvalue is 0.005 inch.

The work rest blade 24 will then hold for a retract time, and will thenrepeat the process until it has reached a "size end" position.

A column of the data in the automatic blade sizing section allows theoperator to set each of the above items individually. The sizingincrements are selectable and may be set to very small or relativelylarge distance increments. The "sizing dwell" is the time for the workrest blade 24 to stay in contact with the work wheel 16. It is common toset the sizing dwell for about ten seconds. However, it can be set to arange of times at 0.1 second increments or smaller.

A WINDOWS screen may also be provided for calibrating transducers (notshown). Such a screen would provide an operator with a consistent and anaccurate process to follow to assure that the ram transducer, which maybe an LVDT, is calibrated to read and display the relative motion of theram regulating wheel 18 with respect to the work wheel 16. Operatorprompts may be provided on this screen in a consistent systematicmanner.

The prompted procedure from this screen may direct the operator to set amicrometer in a particular way and then to input values into thecomputer system. Once the transducer is calibrated, this screen mayprovide means for clicking on an appropriate movement button to checkthe transducer calibration against the size control motor movement.

Numerous help screens, such as the main help screen of FIG. 16 and theblade sizing help screen of FIG. 17 may be included in the presentprogram. These screens may be selected by clicking on the help prompt ofthe main menu bar from the main operating screen and then selectingparticular help screens from the menu bar of the main help screen shownin FIG. 16.

The main help screen may depict an image of the overall centerlessgrinder assembly 10 including the various parts thereof as discussedabove. The helpful information is organized with a table of contents andsearch paths to a specific subject or interest or need. Areas whereinformation is directly available are indicated by the usual WINDOWS"hand" icon where the cursor is placed over an object. The operator canexit from the help screen by clicking on the "exit" button.

A notepad screen is shown in FIG. 18 to provide the operator with anopportunity to take useful operating notes. The WINDOWS based operatingsystem of the present invention provides a particularly user friendlyenvironment to assist the operator in operating the present grinderassembly 10.

While the foregoing description and figures are directed towardpreferred embodiments of the present invention, it should be appreciatedthat numerous modifications can be made to various features of thepresent centerless grinder assembly, and various steps in the methodsset forth above while remaining within the scope and spirit of thepresent invention. Indeed, such modifications are encouraged to be madeto the present centerless grinder assembly and methods of operating thesame. Accordingly, the aforementioned detailed description of thepresent invention should be taken by way of illustration rather than byway of limitation as the present invention is defined by the claims setforth below.

I claim:
 1. A method of operating a centerless grinder assemblycomprising: determining the ideal profile dimensions of an elongateworkpiece to be machined, said ideal profile having a non-uniformdiameter along the length of said workpiece; inputting datarepresentative of the ideal profile dimensions into a computer readablememory of the centerless grinder assembly; placing an elongate workpieceat a desired location on said centerless grinding assembly to be fedpast a work wheel during machining operations; feeding said elongateworkpiece past said work wheel of said centerless grinder assembly toobtain an actual machined workpiece profile, said actual machinedworkpiece profile having a non-uniform diameter along the length of saidworkpiece; continuously measuring the dimensions along the profile ofthe actual machined workpiece by feeding said machined workpiece througha gauging device; converting said measured workpiece profile dimensionsinto digital signals; transmitting said digital signals representativeof said measured workpiece profile dimensions into a computer system ofthe centerless grinder assembly; calculating deviations between theideal inputted workpiece dimensions and the measured workpiecedimensions; transmitting signals representative of the calculateddeviations to means for modifying the profile of the next workpiece tobe machined so that the profile dimensions of the next machinedworkpiece will be at least as close to said inputted ideal workpiecedimensions as the profile dimensions of the previously machinedworkpiece.
 2. The method of claim 1 wherein said step of calculatingdeviations between the ideal inputted workpiece dimensions and themeasured workpiece dimensions is performed by the computer system of thecenterless grinder assembly.
 3. The method of claim 1 wherein the meansfor modifying the profile of the next workpiece to be machined comprisesa stepper motor in combination with a lead screw herein the transmittedsignals are transmitted to said stepper motor which actuates theassociated lead screw to move a regulating wheel either closer orfurther from the work wheel, or toward or further from the work wheel ata faster or slower rate than the previous machining operations so thatprecise profile dimensions can be obtained on the next elongateworkpiece to be machined.
 4. The method of claim 1 wherein the profiledimensions of the next machined workpiece are closer to said inputtedideal dimensions than were the profile dimensions of the previouslymachined workpiece.
 5. A method of operating a centerless grinderassembly comprising the steps of: determining the ideal profiledimensions of an elongate workpiece to be machined; inputting datarepresentative of the ideal profile dimensions into a computer readablememory of the centerless grinder assembly; placing an elongate workpiecehaving a trailing end at a desired location on said centerless grinderassembly to be fed past a plurality of sensors and a work wheel duringmachining operations; determining ideal position data including thedesired position of the regulating wheel with respect to the work wheelof the centerless grinder assembly, and the corresponding position ofthe trailing end of said elongate workpiece with respect to said workwheel; inputting said ideal position data into the computer readablememory of said centerless grinder assembly; feeding said workpiece pastsaid plurality of sensors and said work wheel at an assumed constantvelocity to obtain an actual machined workpiece profile; continuouslydetecting the position of the trailing end of said workpiece withrespect to said work wheel as it passes said plurality of sensors;converting the continuously detected position data into digital signals;transmitting said digital signals representative of the location of saidtrailing end of said workpiece with respect to said work wheel into thecomputer system of the centerless grinder assembly; continuouslymonitoring and detecting the actual position of said regulating wheelwith respect to said work wheel in correspondence with the continuousdetection of said trailing end of said workpiece; comparing thecontinuously detected position data of said trailing end of saidworkpiece and said regulating wheel with respect to said work wheel tothe ideal position data to ascertain deviations therebetween; generatingdeviation signals representative of the deviation between saidcontinuously detected and said ideal position data of said trailing endof said workpiece and said regulating wheel with respect to said workwheel; and transmitting said deviation signals to motor means foreffecting movement of said regulating wheel whereby the relativepositioning of said regulating wheel and said work wheel is adjusted sothat said actual machined workpiece profile will improve.
 6. The methodof claim 5 further comprising the steps of measuring the dimensionsalong the profile of the actual machined workpiece; converting saidmeasured workpiece profile dimensions into digital signals; transmittingsaid digital signals representative of said measured workpiece profiledimensions into the computer system; calculating deviations between theideal inputted workpiece dimensions and the measured workpiecedimensions; and activating said motor means to cause correctivemovements of said regulating wheel during machining of the nextworkpiece so that the profile dimensions of the next workpiece to bemachined will be closer to the inputted ideal workpiece dimensions thanthe profile dimensions of the previously machined workpiece.
 7. Themethod of claim 6 wherein said step of measuring the dimensions of theactual machined workpiece profile is performed by feeding said machinedworkpiece through a gauging device.
 8. The method of claim 5 whereinsaid step of detecting the position of the trailing end of saidworkpiece is performed by photoelectric sensors electrically connectedto said computer systems.
 9. The method of claim 5 wherein said step oftransmitting signals to said motor means comprises the step oftransmitting signals to a stepper motor which actuates an associatedlead screw to move said regulating wheel toward or away from said workwheel.
 10. The method of claim 5 wherein said step of continuouslydetecting the position of said trailing end of said workpiece withrespect to said work wheel comprises activating and initializing a clockeach time said trailing end of said workpiece is detected by one of saidplurality of sensors, and calculating the estimated position of saidtrailing end of said workpiece between successive ones of said pluralityof sensors by multiplying the elapsed time of said clock by the knownvelocity of said workpiece.